Mugs, Nicknames, And Sparks
by WordsAblaze
Summary: (thw pt.3) In which Yaz is an aspiring detective and Thirteen is an eccentric forensic scientist, but neither of them are smart enough to get together like normal people… Written for prompt 'au' in thasmin week 2019, enjoy!


_Not a wild AU but it sort of wrote itself, oops... Didn't really have time to proof-read, pls be kind about mistakes :) And again, I had no time yesterday to post here as well but it was written on time! Three done now, yay :)_

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 **Mugs, Nicknames, And Sparks**

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Yasmin Khan was having one of those days where everything seemed to go wrong and those things seemed to stack on top of each other until the whole day was just one awfully tall tower of wrong.

"Khan, get over here!" her superior yells, obviously expecting her to figure out where he's shouting from and make her way there in the next second.

Yaz sighs and places the file she was reading to one side before hazarding a guess and walking to the only office with a functional heater.

Within seconds, she's being handed a file. "Take this and finish it up for Monday."

One glance at the front page tells her this is basically a set-up. "You can't be serious, we don't even have any forensics for this yet and it won't be accurate if I only use our theories."

Her superior shrugs. "I can give it to someone else if you'd rather stick with coffee runs," he says, his tone casual and irritatingly smug.

"No, I just-"

"It's only Thursday, just go over to the labs or whatever," he says unhelpfully, waving a hand.

Yaz clenches her jaw, ignoring the fact that his tone is almost condescending enough to act as a spark for her terrible day's tower to be set ablaze, and nods. "Consider it done."

It doesn't take her long to quickly wrap things up with the other file, making a note of key points before stashing everything in a drawer, after which a brief glance at the clock tells her she has plenty of time to walk over to the forensics section tonight.

Which she does. After slipping on her trusty leather jacket, of course, because contracting pneumonia really won't help her climb the career ladder at this point. Not that she disrespects anyone who'd be satisfied with the job she has, it's just not the position she really wants to be associated with; personally, she'd rather be in charge.

One fairly short, brisk walk later, Yaz buzzes the intercom on the front door, rubbing her arms to try and stay warm as she stares at the speaker.

Nothing.

She tries again. And again, twice this time, just in case someone's mistaking it for a phone chiming again. Just as she's lifting her hand to press it again - she's nothing if not stubborn - a familiar static sound arrives and the machine buzzes.

"Sorry, bit of a technical issue, and my hands were covered in oil, but it's all good now! Do you want to come in?"

Before Yaz can mess up her reply because of how brilliant that voice is, full of enthusiasm and authenticity and mystery, the unknown person continues: "Of course you do, why else would you be buzzing the… thingy? Sorry, I hope you're not too cold! I'll get some hot chocolate going while you get in!"

And, with that promise of a warm beverage and the ability to charm it's way into Yaz's heart already, the voice is replaced by a cool, mechanical click, signalling that the door's now unlocked.

"Get it together," Yaz mutters to herself, shaking her head before walking in and making her way to the only lab that's allowed to be open this late, all the while wondering how on earth hot chocolate can be made so quickly.

She only manages a knock and a half on the door before a wild flash of gold causes her to pause, after which the door is pulled open and she's met with what might just be the most welcoming smile in all of possible history.

"Hi!" The owner of said smile chirps, holding out a lovely, dark blue mug. "One warm cup of hot chocolate, as promised! Sorry again about the wait!"

Still recovering, Yaz nods, her cold hands warming up as soon as they wrap around the mug. It takes her a second to realise she must look rather rude, just standing there and staring at the perfect head of blonde hair that somehow seems like it's straight out of a magazine.

"I'm Yasmin Khan but just Yaz to my friends," she blurts, then bites her lip as she receives an unusually cheery smile in response.

"Well, come on in, Yaz! I'm Thirteen, and I'm calling you Yaz because we're friends now!"

If nothing else, it's the easiest friendship Yaz had ever established.

Thirteen flashes her a grin as something beeps before all but sprinting to the left, opening the window a little before taking something unrecognisable out of a microwave that seems to have way too many buttons. Briefly, Yaz wonders if those extra buttons have anything to do with how fast a mug of hot chocolate seems to have been made for her.

"Um, I just wanted-" Yaz cuts herself off as the microwave sparks and Thirteen jerks backwards, one arm pulling Yaz behind her as she uses the other hand to rapidly press a series of buttons.

Her heart's racing and she has no idea why, Yaz realises, but she can hazard a good guess.

Thirteen's skin is cool but warm, just the right balance to seem pleasant. Which is just as well, because she'd rather not make a terrible impression on someone that seems to be the only help around. It takes almost an entire two minutes - which Yaz definitely does not count out to distract her from the faint smell of petrichor, metal, and petrol radiating from Thirteen - for the microwave that's probably not really a microwave to stop giving out smoke and finally quieten down.

"Right, sorry about that, I must have miscalculated its capacity for beverage production," Thirteen says brightly, then glances at Yaz's mug of hot chocolate, her face falling considerably. "Was it not very good?"

Finally able to focus a little better, Yaz offers her a smile. "No, no, it's brilliant! It's just- well, it's not every day a microwave almost explodes."

Thirteen nods thoughtfully for a second. "You don't work in here every day so I totally understand that. Do you need to sit down or anything?"

"I'm good, thanks," Yaz replies, "but I do need to collect some evidence."

"Evidence? What for?" Thirteen asks, her nose scrunching up in confusion. "Have I done something wrong already? It usually takes a bit longer than this…"

Yaz shakes her head, both amused and bemused. "You haven't done anything, don't worry, I just need the evidence for the case I've been given, I'm meant to finish it for Monday and I can't really start without the evidence."

"Oh!" Thirteen looks slightly sheepish. "Forensics and all that, yeah, I can do that. I've been doing that ever since I figured out what the word meant… Which case is it again?"

Yaz quickly runs through the case, knowing that she's not meant to reveal too much but also somehow sensing that Thirteen isn't the kind of person to leak details to the media and cause chaos. Slightly too much information sharing or not, Thirteen nods along and disappears as soon as Yaz stops talking, walking through a door Yaz hadn't noticed. Not that that was saying much, Yaz hadn't noticed much else aside from perfect hair and a strangely alluring smile.

"Right, well, we may have a slight problem," Thirteen calls from the side room, then appearing with a pencil behind her ear but nothing in her hands. "There doesn't seem to be anything relevant for your case."

Yaz sighs, letting her eyes shut for a second in frustration.

When she opens them again, wide, curious brown eyes are far too close for her to properly process.

"Woah!" Yaz exclaims, stumbling backwards and regretting it immediately when her foot knocks something solid and unmoving.

Thirteen's hands are instantly steadying her arms, one of her hands then speedily moving to settle around Yaz's wrist to stabilise the mug and prevent either of them getting burned. "Careful there, Yaz."

After steadying herself and using most of her self-control to try and appear unaffected by the warmth on her arms and the sparks flying along her skin, Yaz nods. "What were you doing?"

Thirteen shrugs, stepping back and letting go of Yaz before walking to the back of the room, taking the pencil from her ear and scribbling something into a notebook lying on the counter before tucking the pencil into her pocket.

"Now what are you doing?" Yaz asks, feeling slightly awkward.

"Research!" Thirteen replies eventually. "But don't yourself about it. Is there anything else I can help you with?"

Case forgotten in favour of personal confusion, Yaz asks: "Is your name really Thirteen?"

A knowing look in her eyes, Thirteen grins slyly. "Not quite. It's Doctor J. Thirteen but I've been the cause of enough accidents for unluckily thirteen to become a running joke that turned into a nickname which ended up as my unofficial name!"

Yaz takes a second to process that. It's still a better nickname than some of the ones she's been given, but something else had also caught her attention: "Doctor?"

Thirteen winks. "I did my homework."

After a second, she ruins the slightly ominous atmosphere she'd built up with that by saying: "A lot of homework. Like, seriously, there is a lot of work involved when studying for a PhD."

Chuckling, Yaz takes a small sip of the hot chocolate, her eyes widening at how rich it is. "How did you make this? It's utterly magical!"

"So is your hair and yet I'm not questioning that!" Thirteen fires back immediately, although it's too soft and kind to have been fired, it's more like it's been gently traded.

Either way, Yaz finds herself blushing, glancing down at the hot chocolate with a small smile on her face. Thirteen doesn't say anything and when Yaz looks up again, she's scribbling away in that notebook again, this time with a different pencil that seems to have appeared from nowhere in particular.

"I guess I should get going, then?" Yaz means to use that statement as a goodbye but it ends up as a hesitant question.

Thirteen's eyes widen in what may or may not be blatant disappointment. "Oh. Well. Yes, of course, don't let me keep you or anything."

Honestly, Yaz would like nothing more than for Thirteen to keep her. That's probably why she ends up blurting: "What if I've forgotten where the entrance is?"

"Sorry?" Thirteen frowns, glancing at her hot chocolate as if accusing it of giving her amnesia or another problem along those lines.

Yaz clears her throat, smiling. "I mean, uh, can you walk me out? I think there was a buzzer on one of the doors and I can't remember if it needs a keycard or not so…"

It's almost stupid how the sparks of hope in Thirteen's eyes give her so much happiness. There's just something so purely genuine about them; they're not there to impress anyone or manipulate people, they just explode into existence naturally, and Yaz is rarely so easily impressed.

"It would be a crime to refuse such a simple request from someone as lovely as you, Yaz!"

Thirteen practically bounces towards her, opening the lab doors and gesturing for Yaz to step through. For once, Yaz just accepts it and does so, waiting for Thirteen to fall into step beside her before continuing to walk because of course she knows where the doors are and which of them need identification to unlock but it's way too late to admit that now. Well, that and the fact that she's kind of hoping Thirteen will say her name again; it's never sounded better than when it does coming from her.

They don't say anything until they get back to the main doors, mostly just smiling when they catch one another's eyes, a warmth spreading through Yaz's heart each time they do so. When they do get back to the main doors, though, Thirteen pauses and turns back to her, glancing at the half-full mug with a mischievous look in her eyes.

"You'll have to come back and return my mug, of course. That's one of my favourites," Thirteen says simply.

Yaz nods without thinking and then thinks about it and nods again. "Yeah, of course. There's no way I can condone stealing things!"

"Not even if it involves me stealing you away for an evening?" Thirteen asks, so quietly and so quickly that Yaz barely catches it.

As soon as she figures out what Thirteen is asking, her breath hitches. Before she can give the wrong impression, she raises an eyebrow and smirks. "It wouldn't be stealing if I was to go willingly, now, would it?"

An odd noise escapes Thirteen as she beams, that beautiful spark back in her eyes as she seems to silently thank the mug in Yaz's hand - or maybe that just Yaz - before opening the door with her foot.

"I'll see you tomorrow evening then?" she asks, shivering slightly when the breeze hits her shoulders.

Still a little shocked that that had happened so quickly, Yaz nods rapidly, almost giving herself a headache. "I can't wait!"

"You might have to; time travel seems to still be in the works," Thirteen says, probably not even thinking about it judging by the way she's grinning so happily.

Yaz laughs, the weight of the day easing itself off of her shoulders like smoke. "Take care, Doctor."

She's not even sure why she uses her title as a nickname, it just seems to fit. And Thirteen's not complaining, she just winks and salutes before stepping back a bit so Yaz can get past, murmuring a passionate but soft: "Sweet dreams, Yaz!"

As she heads off and starts her journey back home, intermittently taking sips of what is now definitely the best hot chocolate in the universe, she can't help but think that she might actually have sweet dreams for once because, as if living up to the alternate meanings of her title, Thirteen really has healed something in her and the promise of a date tomorrow is the best medicine Yaz could ever have imagined.

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 _Thanks for reading! Leave a review with thoughts?_


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